Articles
Effect of trunk size on the effectiveness of pistachio harvesters
Article number
1406_40
Pages
273 – 280
Language
English
Abstract
Trunk shakers are the most commonly used mechanical harvesters for shaking pistachio trees in California.
Currently, the duration of applied shaking force and frequency of shaking is set by the operator and usually remains constant for all trees in a given block.
It can be shown that the best shaking frequency and duration are a function of tree canopy characteristics such as size, shape, and branch configuration.
Therefore, shaking all trees in a block with the same shaking frequency and duration might not result in optimum fruit removal for each tree.
Figuring out the optimal shake and duration without getting feedback from the tree is impossible.
Therefore, improving these harvesting machines necessitates a better understanding of the shaking dynamics of the existing trunk shakers during harvest.
In this study, a new sensor system was developed to get feedback on energy input applied to each tree.
Another sensor was developed to determine the fruit removal rate, which can be used to determine the optimal harvest duration time.
The developed sensors were installed on a pistachio harvesting machine, and data was collected during the harvesting season of 2021. In addition to input vibration force, the trunk size of trees was measured.
A significant amount of variability was observed in trees’ responses to the input vibration force.
Also, it was found that the large trees significantly damped the applied vibration at the trunk.
The variability in input energy could cause variability in fruit removal and in some cases, it could cause excessive tree damage.
This effect was different for trees with medium and small trunk sizes.
The fruit removal sensor also demonstrated very promising initial results, however; more data need to be collected to evaluate its effectiveness and also determine the optimal number of needed sensors and their installation location.
Currently, the duration of applied shaking force and frequency of shaking is set by the operator and usually remains constant for all trees in a given block.
It can be shown that the best shaking frequency and duration are a function of tree canopy characteristics such as size, shape, and branch configuration.
Therefore, shaking all trees in a block with the same shaking frequency and duration might not result in optimum fruit removal for each tree.
Figuring out the optimal shake and duration without getting feedback from the tree is impossible.
Therefore, improving these harvesting machines necessitates a better understanding of the shaking dynamics of the existing trunk shakers during harvest.
In this study, a new sensor system was developed to get feedback on energy input applied to each tree.
Another sensor was developed to determine the fruit removal rate, which can be used to determine the optimal harvest duration time.
The developed sensors were installed on a pistachio harvesting machine, and data was collected during the harvesting season of 2021. In addition to input vibration force, the trunk size of trees was measured.
A significant amount of variability was observed in trees’ responses to the input vibration force.
Also, it was found that the large trees significantly damped the applied vibration at the trunk.
The variability in input energy could cause variability in fruit removal and in some cases, it could cause excessive tree damage.
This effect was different for trees with medium and small trunk sizes.
The fruit removal sensor also demonstrated very promising initial results, however; more data need to be collected to evaluate its effectiveness and also determine the optimal number of needed sensors and their installation location.
Authors
A. Toudeshki, R. Ehsani, L. Ferguson
Keywords
mechanical harvester, vibration, fruit removal rate, sensor, energy transfer
Groups involved
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